1. Field
This disclosure relates to a positive active material composition for a rechargeable lithium battery, a positive electrode obtained therefrom, and a rechargeable lithium battery including the same are disclosed.
2. Description of the Related Technology
A rechargeable lithium battery includes positive and negative electrodes and an organic electrolyte solution or a polymer electrolyte positioned between the positive and negative electrodes. Herein, the positive and negative electrodes intercalate and deintercalate lithium ions and produce electrical energy through oxidation and reduction reactions.
As for a positive active material for a lithium rechargeable battery, an oxide that has a structure of intercalating and deintercalating lithium ions and includes lithium and a transition element, for example, a lithium cobalt oxide (LiCoO2), a lithium nickel oxide (LiNiO2), or a lithium nickel cobalt manganese oxide (Li[NiCoMn]O2, Li[Ni1−x−yCoxMy]O2), and the like, have been investigated.
When the positive active material for a rechargeable lithium battery is used with an aqueous binder to fabricate a positive electrode, the positive active material provides unreacted alkali metal ions dissociated into water, which dramatically increases the pH of the positive active material slurry and makes the positive active material slurry strongly basic.
Accordingly, when such an aqueous positive active material slurry having strong basicity is coated on a metal current collector, the metal current collector may be corroded due to the high pH of the material and generate H2 gas and thus, make numerous pinholes on the positive electrode and increase internal resistance of the positive electrode.
In order to solve this problem, Japanese Patent No. 4114247 (2008 Apr. 25) discloses a non-aqueous electrolyte rechargeable battery including a molybdenum trioxide (MoO3) component in a positive electrode. However, the molybdenum trioxide (MoO3) has low electrical conductivity and thus, may increase resistance of an electrode and deteriorate charge and discharge characteristics of the lithium rechargeable battery.
In addition, Japanese Patent Laid-Open Publication No. 2010-021027 (2010 Jan. 28) discloses a method of coating various metal oxides on an Al current collector. However, the method needs additional processing and thus, increases a cost due to the additional processing.
Accordingly, additional research on a novel aqueous positive active material composition to prevent corrosion of a metal current collector is needed.